Electron transfer in ion-atom collisions

The theoretical development of the electron transfer in ion-atom collision is described in this paper. The mathematical formulation of the truncated two-state atomic expansion is introduced. The truncated two-state expansion is valid for collision when charge transfer probability is large or small. It is not valid when the coupling to other states is expected to be important, nor when the adiabatic distortion effect is expected to be significant. The method is generalized to multielectron ion-atom collision. The problem is simplified by adopting active electron approximation. The active electrons are transferred in the collision, and all other electrons are assumed to provide proper screening only. Two different atomic models were applied to describe K-K electron transfer process. Bare projectiles and the target atoms with screened hydrogenic potential are considered. Together with the two-state approximation, this model was applied to calculate the K-K transfer cross sections by light projectiles. Agreement with experimental data was reasonable. (Kato, T.)